Salmon with Indian Curry

recipe adapted fm cookbook "Food of The World"
Ingredients
3 tbsp oil
1 onion - finely sliced
1 ripe tomato - chopped
2 onions - finely chopped
8 garlic cloves - chopped
4 green chillies - chopped
5cm (2-inch) pc ginger - grated
100ml (1/3 cup) tamarind puree
5 tbsp coconut milk
1.2 to 1.5 lb or 1 kg salmon steaks or cutlets

Spice Mix
4 dried chillies -cut into small pcs
1 tbsp cumin seeds
1 tsp coriander seeds
1 tsp mustard seeds
1/4 tsp garam masala
1/2 tsp ground turmeric

Method

1. Prepare the spice mix by grinding the chillies, cumin, coriander and mustard seeds to a fine powder using a spice grinder or pestle and mortar, then mixing with the garam masala and turmeric.
2. Heat oil over low heat in a heavy-based frying pan large enough to hold the pieces of fish in a single layer. 
3. Add the sliced onion and fry until frgrant.  Add the tomato, chopped onion, garlic, green chilli and ginger and fry, stirring occasionally, for 20 minutes, or until the oil separates from the sauce.
4. Add the spice mix and the tarmarind to the pan and bring to a boil.  Add the coconut milk and stir until well mixed.  Season with salt to taste.
5. Add the fish and bring slowly to a boil.  The sauce is not very liquid but it needs to be made very hot in order to cook the fish.  Simmer for 5 minutes, then turn the peices of fish over and simmer for another 5 minutes, or until the fish is cooked through and the sauce is thick.